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authorKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>2008-02-07 00:14:27 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-07 08:42:20 -0800
commit4fca88c87b7969c698912e2de9b1b31088c777cb (patch)
tree6a086aaffb4ec17eadd2f2427c5816a02be6606f /kernel/cgroup.c
parentd2ceb9b7ddedbb2e8e590bc6ce33c854043016f9 (diff)
memory cgroup enhancements: add- pre_destroy() handler
Add a handler "pre_destroy" to cgroup_subsys. It is called before cgroup_rmdir() checks all subsys's refcnt. I think this is useful for subsys which have some extra refs even if there are no tasks in cgroup. By adding pre_destroy(), the kernel keeps the rule "destroy() against subsystem is called only when refcnt=0." and allows css ref to be used by other objects than tasks. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Kirill Korotaev <dev@sw.ru> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Paul Menage <menage@google.com> Cc: Pavel Emelianov <xemul@openvz.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r--kernel/cgroup.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 4d67a39c58a8..4e8b16a8266c 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -586,6 +586,21 @@ static struct inode *cgroup_new_inode(mode_t mode, struct super_block *sb)
return inode;
}
+/*
+ * Call subsys's pre_destroy handler.
+ * This is called before css refcnt check.
+ */
+
+static void cgroup_call_pre_destroy(struct cgroup *cgrp)
+{
+ struct cgroup_subsys *ss;
+ for_each_subsys(cgrp->root, ss)
+ if (ss->pre_destroy && cgrp->subsys[ss->subsys_id])
+ ss->pre_destroy(ss, cgrp);
+ return;
+}
+
+
static void cgroup_diput(struct dentry *dentry, struct inode *inode)
{
/* is dentry a directory ? if so, kfree() associated cgroup */
@@ -2160,6 +2175,13 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
parent = cgrp->parent;
root = cgrp->root;
sb = root->sb;
+ /*
+ * Call pre_destroy handlers of subsys
+ */
+ cgroup_call_pre_destroy(cgrp);
+ /*
+ * Notify subsyses that rmdir() request comes.
+ */
if (cgroup_has_css_refs(cgrp)) {
mutex_unlock(&cgroup_mutex);

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